Static Synchronous Compensator Controller Research Articles

VOLTAGE FLICKER MITIGATION USING GTOBASED STATCOM TO IMPROVE POWER QUALITY OF A MULTI MACHINE SYSTEM

Transmission networks of modern power systems are becoming increasingly stressed because of growing demand and restrictions on building new lines. One of the consequences of such a stressed system is the threat of losing stability following a disturbance. Flexible ac transmission system (FACTS) devices are found to be very effective in a transmission network for better utilization of its existing facilities without sacrificing the desired stability margin. FACTS such as Static Synchronous Compensator (STATCOM), employ the latest technology of power electronic switching devices in electric power transmission systems to control voltage and power flow. The STATCOM adjusts voltage at its terminal by managing the amount of reactive power injected into or absorbed from the power supply. When the system voltage is low, STATCOM creates reactive power; when the system voltage is high, STATCOM absorbs reactive power. In this paper STATCOM controllers are designed for improving transient stability of multi machine systems. Proposed controllers are implemented under MATLAB/SIMULNK environment. Results of PI based controllers installed with multi machine system is found to be better on comparison with conventional system.

Controlling the effectiveness of STATCOM using ANFIS based on PI controller

This research achieves two goals, the first is the modelling of the static synchronous compensator (STATCOM) and design of the control circuits for current, voltage and d.c capacitor voltage (Vd.c) to improve the power factor (PF) by preparing the reactive power by STATCOM so that its work is similar to the work of a synchronous condenser, and the second goal is to use smart techniques to control the Vd.c loop. For comparison, smart technical methods such as fuzzy logic type 1 (FL-T1), fuzzy logic type 2 (FL-T2), and adaptive neuro fuzzy inference system (ANFIS) were used to regulate the Vd.c on the capacitor instead of the traditional controller proportional integral (PI). Simulation was performed in MATLAB 2021 to determine the efficiency of the suggested method or approach controllers for STATCOM. The use of the proposed method improves the signal value of both the current and the voltage and the phase difference between them, which reaches almost zero. Proved that an ANFIS technique provides best Vd.c response in different values of balance and unbalance load compared with the other methods by obtaining the minimum peak overshoot (P-ov) and minimum settling time (ST).

Voltage Profile Improvement Using Static Synchronous Compensator STATCOM

Static synchronous compensator (STATCOM) is a regulating device used in AC transmission systems as a source or a sink of reactive power. The most common use of the STATCOM is in improving the voltage stability of the transmission system. A voltage regulator is a custom power device used to correct the voltage disturbance by injecting controllable voltage as well power into the system. This paper implement Nruro-Fuzzy controller to control the STATCOM to improve the voltage profile of the power system The strategy of STATCOM controller is to keep the voltage in the nominal range. The controller has been simulated after some kinds of disturbances and the results show improvements in voltage profile of the system.

Selective Harmonic Voltage Control for STATCOMs in Wind Power Plants

This paper proposes a selective harmonic voltage control approach for the static synchronous compensator (STATCOM) deployed in wind power plants (WPPs). The method enables STATCOM to mitigate voltage harmonics at the point of interconnection of WPP without using the high-voltage sensor. Further, a passivity-based design of the proposed control method is developed to eliminate the negative resistances around the concerned harmonic components, which allows robust harmonic voltage damping under the different passive grid impedances. The effectiveness of the approach is elaborated by theoretical analysis and validated by electromagnetic simulations.

An An Optimal Placement of STATCOM Controller on 14-Bus IEEE Standard Test Transmission Network Using Particle Swarm Optimization

The bulk transport of electrical energy from a generating station to an electrical substation is facilitated by transmission network. Transmission network suffered from unavoidable power loss and there is need to minimize the loss so as to improve the overall efficiency of the network. By strategically placing Static Synchronous Compensator (STATCOM) controller into appropriate location, power loss can be reduced. Factually, one of the most crucial Flexible Alternating Current Transmissions (FACTS) device that control electrical power and increase system power transfer capability is considered as STATCOM. STATCOM is typically installed on the transmission network to reduce power losses and improve the voltage profile of the system. To significantly reduce power losses and improve the system voltage profile, which will ensure the security and dependability of the power system, this research looks into the optimal placement of STATCOM controller on transmission system using Particle Swarm Optimization (PSO) technique. A steady state mathematical model of STATCOM-based Power Injection Mode (PIM) through voltage source representation was derived. The mathematical model was implemented into Newton-Raphson (NR) load flow and PSO technique was used to optimize the exact location of STATCOM in objective to minimize power losses, improve voltage magnitude profile and provide adequate voltage stability to the power system. The voltage magnitude, active and reactive power loss were achieved for load flow solution on 14-bus IEEE test system using Power System Analysis Toolbox (PSAT) in MATLAB Simulink. Results revealed that, all the terminal voltages are within the voltage limits of 1.040 p.u and 1.035 p.u., respectively. The total active and reactive power losses were able to reduce by 6.90 % and 9.13 % respectively. The STATCOM based PSO optimal placement gave a stronger compensatory impact because it helped to reduce power losses and improved the overall network STATCOM-based profile.

A review of the STATCOM device for improving wind farm stability

This review article presents an overview of the Static Synchronous Compensator (STATCOM) device, its working principle, and its application for improving the stability of wind farms. The article also highlights the importance of STATCOMs in enhancing the power quality of wind farms by improving voltage stability, reducing power fluctuations, and mitigating grid faults. Due to continuously fluctuating wind speeds and faults, the active power, reactive power, and terminal voltage are susceptible to continuous change, which applies to terminal voltage as well. When a STATCOM is connected to the grid, the active power, reactive power, and terminal voltage are maintained at the same level during the connection. This also contributes to an increase in the system's transient stability, which is an important consideration. The review further describes the modeling and control of STATCOMs, including the selection of appropriate control strategies for specific wind farm applications. Finally, the article concludes with a summary of the future research directions for the STATCOM device and its potential for integration into the smart grid.

Analysis of Power Quality Problems on Nigerian 330 kV Power System Using Statcom with Voltage Sensitivity Index

Transmission system is the transportation of electrical energy from generating stations to load centers. However, increase usage of non-linear loads from the consumers has led to electrical Power Quality (PQ) problems which have negative impacts on the operation of the power system especially Nigerian power system. This research analyzed the PQ problem on Nigerian 330 kV power system. Newton-Raphson (NR) iterative method was used to performed load flow analysis on Nigerian 28-bus transmission systems. Then power injection model of the Static Synchronous Compensator (STATCOM) was incorporated to modify the NR mathematical model. The suitable placement for the STATCOM in the system was determined using Voltage Sensitivity Index (VSI) and simulation was done in MATLAB/SIMULINK. The results showed that, the suitable placements of STATCOM controller in the power system were buses 5, 8, 12 and 16. The corresponding STATCOM reactive power, sag voltage and sag duration for buses 5, 8, 12 and 16 were 72.56 MVar, 0.77454 p.u, 0.7336s; 65.35 Mvar, 0.7464 p.u, 0.7419 s; 50.86 Mvar, 0.7615 p.u, 0.6512 s and 53.75 MVar, 0.7442 p.u. 0.5972 s, respectively. Therefore, the results have established the importance of STATCOM with VSI in obtaining suitable solution for PQ problems on electrical power system. Keywords: Transmission System, Electrical Energy, Non-linear Load, Power Quality, Newton-Raphson, STATCOM, Voltage Stability Index. DOI: 10.7176/ISDE/12-6-03 Publication date: October 31 st 2022

Research on coordinated control of flexible on-load voltage regulator and STATCOM

Traditional on-load tap changer (OLTC) has problems such as easy oscillation and low regulation precision in the voltage regulation control of the power system. In order to seek a speedy and stable voltage control strategy, a flexible on-load voltage regulator is studied in this paper. A stepless energy take-off winding is set on the high-voltage side to connect the back-to-back converter, and the winding side of the converter is used to realize reactive power compensation. The grid side of the converter can realize continuous voltage regulation. A coordinated voltage regulation control strategy between flexible on-load voltage regulator and static synchronous compensator (STATCOM) is proposed. The tap positions of the flexible on-load voltage regulator and the reactive power sent by the STATCOM are used as reference signals to ensure sufficient capacity of the compensator and reduce the number of tap actions. The strategy proposed in this paper is compared with the voltage regulation method based on the traditional voltage regulation devices, the effectiveness of the strategy is demonstrated by some simulations based on Matlab/Simulink.

Complying the LVRT grid code requirement of a fixed speed wind energy system using unified voltage and pitch angle control strategy

This paper proposes a Unified Voltage and Pitch angle Control (UVPC) strategy for fixed speed wind farm. The focus put on guaranteeing the LVRT grid code requirement when the wind farm subjected to severe faults. The UVPC consist of static synchronous compensator (STATCOM) voltage control loops with adequate pitch angle control loops which are coordinated to enhance the low-voltage ride-through capability of the wind generators thereby, complying the low voltage ride through (LVRT) grid code requirement as desired by the Germany grid code. Different scenarios such as system without STATCOM and pitch-angle controller, with STATCOM only, and system with STATCOM and pitch-angle control (i.e. UVPC) are simulated. The simulation results show that the adoption of STATCOM and pitch angle controller fulfilling the LVRT grid code requirement to ensure the continuous operation of wind turbines. Furthermore, a concept of critical clearing time (CCT) is discussed and its utility has been emphasized. Calculations, simulations and measurements provide how the increased STATCOM rating can offer an enhanced stability margin.

Comparative study of battery-based STATCOM in grid-following and grid-forming modes for stabilization of offshore wind power plant

This paper presents a comparative analysis of a static synchronous compensator (STATCOM) based on battery energy storage system with grid-following and grid-forming operations utilized for stability enhancement of offshore wind power plants (WPPs). The small-signal model of a typical offshore WPP system is developed first, then compared from two perspectives – oscillation index for stability margin evaluation of a multi-input multi-output system and damping ratio of dominant poles, with respect to the critical control parameters. The theoretical comparative analysis proves that the grid-forming control offers evident stability margin and damping to the WPPs especially in weak grids, superior to the grid-following STATCOM. This conclusion holds true for most conditions with properly designed parameters, including different bandwidths of the alternating voltage control of STATCOM in 1∼10 Hz and phase-locked loop of grid-following STATCOM ranging from 5 to 100 Hz, which is benefited from the sufficient stability margin of GFM mode. The small-signal models and comparative analysis are corroborated by electromagnetic transients (EMT) simulations.

Shunt compensation for mitigation of harmonics, voltage sags, and flickers using new STATCOM control scheme

AbstractVoltage sags flickers, and harmonics are major problems associated with power quality and are of concern to power companies and consumers. Therefore, efforts to improve power quality have increased. This study explores the dynamic performance of a static synchronous compensator (STATCOM), which is used to mitigate voltage sags, flickers, and harmonics using a novel control method. Further, the ability of the STATCOM system to alleviate issues related to power quality while, in addition, improving the transmission/distribution system performance concerning all disturbances and errors related to the system is validated. The methodology of this research adopts MATLAB/SIMULINK to perform the requested simulations, which were analysed accordingly. The results show an improvement in the system performance between 40% and 80%, demonstrating the ability of the newly designed controller for a STATCOM to alleviate voltage sags, flickers, and harmonics.

Coordinated design of PSS and STATCOM-POD based on the GA-PSO algorithm to improve the stability of wind-PV-thermal-bundled power system

The application of renewable energy has a significant impact on the stability of power systems. This article jointly uses static synchronous compensator (STATCOM), additional power oscillation damping (POD) controller and power system stabilizers (PSSs) to improve the stability of power systems in transmission network. An enhanced intelligent optimization algorithm is utilized to optimize the controller parameters. The proposed algorithm introduces the idea of combined genetic algorithm (GA) and particle swarm algorithm (PSO) to overcome the local convergence problem of the PSO. The voltage control and damping control of STATCOM are comprehensively considered in the objective function to suppress low-frequency power oscillation (LFO) while ensuring the effectiveness of voltage control. Numerical results from the IEEE 4 machine 2 area system and the IEEE 16-machine five-areas system demonstrate the effectiveness of the proposed method and the superiority on restraining the LFO of the wind-PV-thermal-bundled (WPTB) system.

STATCOM control strategies in energy-function-based methods for the globally optimal control of renewable sources during transients

The inclusion of large numbers of renewable energy sources (RESs) can lead to the operation of electric-power systems close to their natural stability limits. To improve stability, the flexibility and fast control of RESs can be exploited. However, RESs must be “told” what to do for the sake of the “common good”. One possibility is to apply global control based on energy functions, but this requires the appropriate mathematical tools and models. In addition to the “real power feed”, the RESs’ power converters, among others, offer the functionality of a static synchronous compensator (STATCOM). Therefore, the aim of this paper was to develop energy functions for a STATCOM—the ones that consider its control strategies and limitations—that can be applied in energy-function-based methods for a transient-stability assessment and improvement. The two main contributions of this paper derive from the developed energy function (EF). The first contribution is the ability to use a direct method for the transient-stability assessment of an EPS that includes STATCOMs. The second contribution is the application of the developed EF in the control strategies of STATCOM and RES for a globally optimal, transient-stability improvement that can be used as a reference for other, simpler and more applicable control strategies. Such a reference has not existed until now. The STATCOM’s energy functions were developed as additional expressions that can be added to the already-known energy function of the electric-power system in the structure-preserving frame. The correctness of the developed energy functions was proved by applying them in a direct method for the transient-stability assessment and a comparison of these results with those obtained with a numerical simulation. Examples of the use of energy functions for the control of a STATCOM’s reactive current show how the STATCOM can improve the transient stability in a globally optimal way and can be used as a reference for a STATCOM’s simpler control strategies based on local parameters. An example of a RES’s reactive current control that is based on the developed energy functions shows that the RES can be successfully applied for a transient-stability enhancement. The paper can be seen as the first step towards a globally optimal control of the RES during transients.

Performance Analysis of ANFIS-PSO based STATCOM in an Isolated Renewable Energy based Micro-Grid

In recent times, the micro-grids have gained more importance owing to the increased need for providing reliable and quality power to the users at remote locations. This work proposes a novel application of Adaptive Neuro-Fuzzy Inference System (ANFIS) in conjunction with Particle Swarm Optimization (PSO)-based controller for static synchronous compensator to improve the performance of a hybrid renewable energy based isolated micro grid environment. Adaptive and robust ANFIS controller combines the features of artificial neural network and fuzzy inference system. The proposed controller provides reactive power compensation and maintains the stability of the system. The functionality of the system is tested in MATLAB/Simulink under varying conditions and results show improvement in power factor and reduction in harmonics. Also, the performance of PSO-ANFIS is superior to conventional PI and ANFIS controller in terms error components.

Isolated microgrid stability reinforcement using optimally controlled STATCOM

This paper presents optimal control of static synchronous compensator (STATCOM) intended for the application in isolated microgrids using genetic optimizers. The main objectives are to enhance the microgrid stability and reduce the oscillations in voltage, power, and frequency at different operating conditions. The proposed microgrid is a hybrid power system consisting of a diesel generator and a wind turbine each rated at 500 kW. The microgrid is supplying standalone static/dynamic loads rated at 500 kW. The wind turbine unit is controlled to operate at maximum power point tracking (MPPT). The diesel unit is used for ensuring the generation-demand equilibrium is maintained particularly under low wind speeds. The paper mainly discusses the voltage and frequency regulation of the isolated microgrid at different conditions such as: sudden changes in wind speed and/or load variations. Moreover, the proposed microgrid operation is examined under abnormal three-phase short circuit condition at the point of common coupling (PCC). To guarantee the microgrid voltage and frequency regulation at these diverse operating conditions, an optimally controlled STATCOM is considered as a reactive power source. The multi-objective genetic algorithm (GA) is used to obtain the optimal scheduling of the STATCOM controller’s gains without any delay in the control signal. From the simulation results, using Matlab™, the performance of the microgrid is improved and the oscillations in voltage, frequency, and power are reduced. The microgrid stability is enhanced using STATCOM device.

Reactive Power Control using STATCOM for Power System Voltage Improvement

Stability of power system is the ability of the system, with a certain initial operation conditions, to restore the operating balance conditions after exposure to disturbance such as faults or sudden load changes. More attention is required to address voltage instability problems to keep voltage profile under control during abnormal conditions. This paper proposes a Static Synchronous Compensator (STATCOM) using (MATLAB / Simulink Program) The STATCOM includes proportional-integral (PI) control model is used to control the voltage during abnormal conditions by absorbing or injecting reactive power into the power system. Simple and reliable PI controller has been used and designed to be stable under various operating conditions. Three phase Two level PWM strategy technic used in STATCOM controller to decrease the harmonics injected after adding STATCOM to the power system (THD = 2.21%). The simulation study has been done by using 9 buses IEEE system after making a disturbance such as sudden load change. Then the voltage profile during this interval is being studied with and without using STATCOM. The simulation results show that adding STATCOM to this system led to improve the voltage profile during disturbance interval and made the system more stable and reliable by preventing the disturbance effects from reaching the generation side (Vbus 5 = 0.8980 pu, during disturbance before adding STATCOM, Vbus 5 = 1.0003 pu, during disturbance after adding STATCOM). The fast response of the STATCOM controller gives the ability of injecting or absorbing reactive power during disturbances and keeping the system voltages within the IEEE standards limits (0.95 pu > V> 1.05 pu).

A review ofSTATCOMcontrol for stability enhancement of power systems with wind/PVpenetration: Existing research and future scope

In recent years, the development of renewable energy sources (RESs) and their integration with the conventional power network have increased significantly. Due to the power grid transformation brought about by the large penetration of power electronics converter-based RESs such as wind and solar photovoltaic (PV), the operation and control of the interconnected power system has become a challenging task with respect to sustaining its stability and reliability. Power systems are confronted by several new stability issues because the dynamic behavior of converter-interfaced renewable sources differs from conventional generation. In this respect, static synchronous compensator (STATCOM), a shunt connected flexible AC transmission system (FACTS), is recognized as a fundamental solution for maintaining power system stability. This paper presents a thorough and state-of-the-art review of STATCOM control in wind- and/or PV-interfaced power systems for enhancing system performance by addressing key stability issues related to rotor angle stability, voltage stability, and resonance stability. A comprehensive analysis of various control techniques of STATCOM based on conventional, adaptive, nonlinear, predictive, robust, and coordinated control and soft computing techniques is provided. Furthermore, the function of the grid-side converter of the wind/PV plant as a STATCOM is also evaluated. Finally, the shortcomings of existing research are highlighted, current control challenges are presented, and several topics for future research are suggested. This paper provides researchers the opportunity to consider the current state of research and develop new control schemes for STATCOM to further improve the stability of modern power grids.

An Improved Adaptive Passive Coordinated Control for Generator Excitation and STATCOM

An improved adaptive backstepping passive coordinated control strategy is proposed to deal with the uncertainty of damping coefficient and mechanical power and external disturbance on the system stability. A nonlinear coordinated controller of generator excitation and STATCOM (static synchronous compensator) is designed to improve its adaptability. The adaptive estimation laws of damping coefficient and mechanical power are designed by using I&I (immersion and invariance) adaptive control to improve the adaptive ability of the controller. Based on the backstepping recursive method, the control law of STATCOM is designed and combines the passivity theory, thus acquiring the control law of generator excitation. In the backstepping design, the derivative of the virtual control input and external disturbance are considered to be uncertain, and the nonlinear damping algorithm is introduced to reduce the “calculation explosion.” Simulation results show that the designed controller improves the stability of the power system and shows strong adaptability and robustness.

Stability Enhancement of DFIG Based Wind Turbine Under Three Phase Fault with STATCOM

The main aim of this paper is to improve the transient stability of Doubly Fed Induction Generator (DFIG) based wind turbine using Static Synchronous Compensator (STATCOM). In this paper, a multi-objective problem is formulated to minimize voltage deviations at the point of common coupling (PCC) and mitigate low frequency oscillations after clearing the faults. Genetic algorithm based STATCOM controller is used to enhance the stability of a grid-connected wind farm composed of a variable-speed wind turbine generator system (WTGS). The transient performance of the proposed control scheme is analyzed with a three-phase fault. The Simulations are carried out in MATLAB/Simulink environment.

Model-Free Adaptive Control of STATCOM for SSO Mitigation in DFIG-Based Wind Farm

As the wind-integrated power system is a strongly nonlinear system with uncertain operating conditions that vary with time, it is difficult to guarantee the effectiveness of the conventional model-based sub-synchronous damping control (SSDC). To solve this problem, a model-free adaptive control (MFAC) method for static synchronous compensator (STATCOM) is proposed to realize sub-synchronous oscillation (SSO) mitigation. The method is driven by a limited number of online input/output (I/O) data rather than full technical and operational details of the system. First, the structure of the proposed MFAC is described in detail with control algorithms of all modules. Particularly, a new form of one-step-ahead weighted predictive control algorithm of MFAC for SSO mitigation is proposed. Then, the convergence of tracking error along with the stability of the closed-loop system with the improved MFAC are analyzed. Finally, the performance of the proposed MFAC for STATCOM is demonstrated and compared with that of the conventional SSDC under various operating conditions. Time domain simulation results validate the effectiveness of the proposed MFAC and demonstrate its better adaptability than the conventional SSDC.